Add documentation

sinks/README.md

@@ -2,17 +2,24 @@
 
 This folder contains the SinkManager and sink implementations for the cc-metric-collector.
 
+# Available sinks:
+- `stdout`: Print all metrics to `stdout`, `stderr` or a file
+- `http`: Send metrics to an HTTP server as POST requests
+- `influxdb`: Send metrics to an InfluxDB database
+- `nats`: Publish metrics to the NATS network overlay system
+- `ganglia`: Publish metrics in the [Ganglia Monitoring System](http://ganglia.info/)
+
 # Configuration
 
 The configuration file for the sinks is a list of configurations. The `type` field in each specifies which sink to initialize.
 
 ```json
 [
-  {
+  "mystdout" : {
     "type" : "stdout",
     "meta_as_tags" : false
   },
-  {
+  "metricstore" : {
     "type" : "http",
     "host" : "localhost",
     "port" : "4123",
@@ -22,74 +29,12 @@ The configuration file for the sinks is a list of configurations. The `type` fie
 ]
 ```
 
-This example initializes two sinks, the `stdout` sink printing all metrics to the STDOUT and the `http` sink with the given `host`, `port`, `database` and `password`.
-
-If `meta_as_tags` is set, all meta information attached to CCMetric are printed out as tags.
-
-## Type `stdout`
-
-```json
-{
-  "type" : "stdout",
-  "meta_as_tags" : <true|false>
-}
-```
-
-The `stdout` sink dumps all metrics to the STDOUT.
-
-## Type `http`
-
-```json
-{
-  "type" : "http",
-  "host" : "<hostname>",
-  "port" : "<portnumber>",
-  "database" : "<database name>",
-  "password" : "<jwt token>",
-  "meta_as_tags" : <true|false>
-}
-```
-The sink uses POST requests to send metrics to `http://<host>:<port>/<database>` using the JWT token as a JWT in the 'Authorization' header.
-
-## Type `nats`
-
-```json
-{
-  "type" : "nats",
-  "host" : "<hostname>",
-  "port" : "<portnumber>",
-  "user" : "<username>",
-  "password" : "<password>",
-  "database" : "<database name>"
-  "meta_as_tags" : <true|false>
-}
-```
-
-This sink publishes the CCMetric in a NATS environment using `host`, `port`, `user` and `password` for connecting. The metrics are published using the topic `database`. 
-
-## Type `influxdb`
-
-```json
-{
-  "type" : "influxdb",
-  "host" : "<hostname>",
-  "port" : "<portnumber>",
-  "user" : "<username>",
-  "password" : "<password or API key>",
-  "database" : "<database name>"
-  "organization": "<InfluxDB v2 organization>",
-  "ssl" : <true|false>,
-  "meta_as_tags" : <true|false>
-}
-```
-
-This sink submits the CCMetrics to an InfluxDB time-series database. It uses `host`, `port` and `ssl` for connecting. For authentification, it uses either `user:password` if `user` is set and only `password` as API key. The `organization` and `database` are used for writing to the correct database.
 
 
 
 # Contributing own sinks
-A sink contains three functions and is derived from the type `Sink`:
+A sink contains four functions and is derived from the type `sink`:
-* `Init(config SinkConfig) error`
+* `Init(config json.RawMessage) error`
 * `Write(point CCMetric) error`
 * `Flush() error`
 * `Close()`
@@ -97,3 +42,52 @@ A sink contains three functions and is derived from the type `Sink`:
 The data structures should be set up in `Init()` like opening a file or server connection. The `Write()` function writes/sends the data. For non-blocking sinks, the `Flush()` method tells the sink to drain its internal buffers. The `Close()` function should tear down anything created in `Init()`.
 
 Finally, the sink needs to be registered in the `sinkManager.go`. There is a list of sinks called `AvailableSinks` which is a map (`sink_type_string` -> `pointer to sink interface`). Add a new entry with a descriptive name and the new sink.
+
+## Sample sink
+
+```go
+package sinks
+
+import (
+	"encoding/json"
+	"log"
+	lp "github.com/ClusterCockpit/cc-metric-collector/internal/ccMetric"
+)
+
+type SampleSinkConfig struct {
+	defaultSinkConfig  // defines JSON tags for 'name' and 'meta_as_tags'
+}
+
+type SampleSink struct {
+	sink              // declarate 'name' and 'meta_as_tags'
+	config StdoutSinkConfig // entry point to the SampleSinkConfig
+}
+
+// Initialize the sink by giving it a name and reading in the config JSON
+func (s *SampleSink) Init(config json.RawMessage) error {
+	s.name = "SampleSink"   // Always specify a name here
+  // Read in the config JSON
+	if len(config) > 0 {
+		err := json.Unmarshal(config, &s.config)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Code to submit a single CCMetric to the sink
+func (s *SampleSink) Write(point lp.CCMetric) error {
+	log.Print(point)
+	return nil
+}
+
+// If the sink uses batched sends internally, you can tell to flush its buffers
+func (s *SampleSink) Flush() error {
+	return nil
+}
+
+
+// Close sink: close network connection, close files, close libraries, ...
+func (s *SampleSink) Close() {}
+```

sinks/gangliaSink.md

@@ -0,0 +1,21 @@
+## `ganglia` sink
+
+The `ganglia` sink uses the `gmetric` tool of the [Ganglia Monitoring System](http://ganglia.info/) to submit the metrics
+
+### Configuration structure
+
+```json
+{
+  "<name>": {
+    "type": "ganglia",
+    "meta_as_tags" : true,
+    "gmetric_path" : "/path/to/gmetric",
+    "add_ganglia_group" : true
+  }
+}
+```
+
+- `type`: makes the sink an `ganglia` sink
+- `meta_as_tags`: print all meta information as tags in the output (optional)
+- `gmetric_path`: Path to `gmetric` executable (optional). If not given, the sink searches in `$PATH` for `gmetric`.
+- `add_ganglia_group`: Add `--group=X` based on meta information to the `gmetric` call. Some old versions of `gmetric` do not support the `--group` option. 

sinks/httpSink.md

@@ -0,0 +1,25 @@
+## `http` sink
+
+The `http` sink uses POST requests to a HTTP server to submit the metrics in the InfluxDB line-protocol format. It uses JSON web tokens for authentification. The sink creates batches of metrics before sending, to reduce the HTTP traffic.
+
+### Configuration structure
+
+```json
+{
+  "<name>": {
+    "type": "http",
+    "meta_as_tags" : true,
+    "database" : "mymetrics",
+    "host": "dbhost.example.com",
+    "port": "4222",
+    "jwt" : "0x0000q231",
+  }
+}
+```
+
+- `type`: makes the sink an `http` sink
+- `meta_as_tags`: print all meta information as tags in the output (optional)
+- `database`: All metrics are written to this bucket 
+- `host`: Hostname of the InfluxDB database server
+- `port`: Portnumber (as string) of the InfluxDB database server
+- `jwt`: JSON web tokens for authentification

sinks/influxSink.md

@@ -0,0 +1,32 @@
+## `influxdb` sink
+
+The `influxdb` sink uses the official [InfluxDB golang client](https://pkg.go.dev/github.com/influxdata/influxdb-client-go/v2) to write the metrics to an InfluxDB database. It provides only support for V2 write endpoints (InfluxDB 1.8.0 or later).
+
+
+### Configuration structure
+
+```json
+{
+  "<name>": {
+    "type": "influxdb",
+    "meta_as_tags" : true,
+    "database" : "mymetrics",
+    "host": "dbhost.example.com",
+    "port": "4222",
+    "user": "exampleuser",
+    "password" : "examplepw",
+    "organization": "myorg",
+    "ssl": true,
+  }
+}
+```
+
+- `type`: makes the sink an `influxdb` sink
+- `meta_as_tags`: print all meta information as tags in the output (optional)
+- `database`: All metrics are written to this bucket 
+- `host`: Hostname of the InfluxDB database server
+- `port`: Portnumber (as string) of the InfluxDB database server
+- `user`: Username for basic authentification
+- `password`: Password for basic authentification
+- `organization`: Organization in the InfluxDB
+- `ssl`: Use SSL connection

sinks/natsSink.md

@@ -0,0 +1,28 @@
+## `nats` sink
+
+The `nats` sink publishes all metrics into a NATS network. The publishing key is the database name provided in the configuration file
+
+
+### Configuration structure
+
+```json
+{
+  "<name>": {
+    "type": "nats",
+    "meta_as_tags" : true,
+    "database" : "mymetrics",
+    "host": "dbhost.example.com",
+    "port": "4222",
+    "user": "exampleuser",
+    "password" : "examplepw"
+  }
+}
+```
+
+- `type`: makes the sink an `nats` sink
+- `meta_as_tags`: print all meta information as tags in the output (optional)
+- `database`: All metrics are published with this subject
+- `host`: Hostname of the NATS server
+- `port`: Portnumber (as string) of the NATS server
+- `user`: Username for basic authentification
+- `password`: Password for basic authentification

sinks/stdoutSink.md

@@ -0,0 +1,22 @@
+## `stdout` sink
+
+The `stdout` sink is the most simple sink provided by cc-metric-collector. It writes all metrics in InfluxDB line-procol format to the configurable output file or the common special files `stdout` and `stderr`.
+
+
+### Configuration structure
+
+```json
+{
+  "<name>": {
+    "type": "stdout",
+    "meta_as_tags" : true,
+    "output_file" : "mylogfile.log"
+  }
+}
+```
+
+- `type`: makes the sink an `stdout` sink
+- `meta_as_tags`: print all meta information as tags in the output (optional)
+- `output_file`: Write all data to the selected file (optional). There are two 'special' files: `stdout` and `stderr`. If this option is not provided, the default value is `stdout`
+
+